The Untapped Pharmacopeic Potential of Helminths

Anti-Inflammatory Responses Produced with Nippostrongylus brasiliensis-Derived Uridine via the Mitochondrial ATP-Sensitive Potassium Channel and Its Anti-Atherosclerosis Effect in an Apolipoprotein E Gene Knockout Mouse Model

Atherosclerosis (AS) has become the leading cause of cardiovascular disease worldwide. Our previous study had observed that Nippostrongylus brasiliensis (Nb) infection or its derived products could inhibit AS development by inducing an anti-inflammatory response. We performed a metabolic analysis to screen Nb-derived metabolites with anti-inflammation activity and evaluated the AS-prevention effect. We observed that the metabolite uridine had higher expression levels in mice infected with the Nb and ES (excretory-secretory) products and could be selected as a key metabolite. ES and uridine interventions could reduce the pro-inflammatory responses and increase the anti-inflammatory responses in vitro and in vivo. The apolipoprotein E gene knockout (ApoE-/-) mice were fed with a high-fat diet for the AS modeling. Following the in vivo intervention, ES products or uridine significantly reduced serum and liver lipid levels, alleviated the formation of atherosclerosis, and reduced the pro-inflammatory responses in serum or plaques, while the anti-inflammatory responses showed opposite trends. After blocking with 5-HD (5-hydroxydecanoate sodium) in vitro, the mRNA levels of M2 markers were significantly reduced. When blocked with 5-HD in vivo, the degree of atherosclerosis was worsened, the pro-inflammatory responses were increased compared to the uridine group, while the anti-inflammatory responses decreased accordingly. Uridine, a key metabolite from Nippostrongylus brasiliensis, showed anti-inflammatory and anti-atherosclerotic effects in vitro and in vivo, which depend on the activation of the mitochondrial ATP-sensitive potassium channel.

Protozoan-Derived Cytokine-Transgenic Macrophages Reverse Hepatic Fibrosis

Macrophage therapy for liver fibrosis is on the cusp of meaningful clinical utility. Due to the heterogeneities of macrophages, it is urgent to develop safer macrophages with a more stable and defined phenotype for the treatment of liver fibrosis. Herein, a new macrophage-based immunotherapy using macrophages stably expressing a pivotal cytokine from Toxoplasma gondii, a parasite that infects ≈ 2 billion people is developed. It is found that Toxoplasma gondii macrophage migration inhibitory factor-transgenic macrophage (Mφtgmif) shows stable fibrinolysis and strong chemotactic capacity. Mφtgmif effectively ameliorates liver fibrosis and deactivates aHSCs by recruiting Ly6Chi macrophages via paracrine CCL2 and polarizing them into the restorative Ly6Clo macrophage through the secretion of CX3CL1. Remarkably, Mφtgmif exhibits even higher chemotactic potential, lower grade of inflammation, and better therapeutic effects than LPS/IFN-γ-treated macrophages, making macrophage-based immune therapy more efficient and safer. Mechanistically, TgMIF promotes CCL2 expression by activating the ERK/HMGB1/NF-κB pathway, and this event is associated with recruiting endogenous macrophages into the fibrosis liver. The findings do not merely identify viable immunotherapy for liver fibrosis but also suggest a therapeutic strategy based on the evolutionarily designed immunomodulator to treat human diseases by modifying the immune microenvironment.

Echinococcus granulosus as a Promising Therapeutic Agent against Triplenegative Breast Cancer

Abstract:

Breast cancer is a major cause of cancer deaths in women, with approximately 1.2 million new cases per year. Current treatment options for breast cancer include surgery, radiation, hormone therapy, and chemotherapy. However, the non-selective cytotoxicity of chemotherapeutic agents often leads to severe side effects, while drug resistance can worsen patient outcomes. Therefore, the development of more effective and less toxic anticancer drugs is a critical need. This study aimed to review the literature on Echinococcus granulosus antigens with anticancer potential against triple-negative breast cancer. Recent studies have suggested that certain parasite antigens may have potential anticancer effects. Specifically, research has shown that echinococcosis, a disease caused by the parasitic cestode Echinococcus granulosus, may have a protective effect against cancer. These findings offer new insights into the potential use of E. granulosus antigens in the development of novel cancer therapies and tumor cell vaccines. The findings of recent studies suggested that E. granulosus antigens may have the potential to be used in effective and less toxic cancer treatments. However, further research is needed to fully understand the mechanisms behind the anticancer effects of these antigens and develop new cancer therapies and vaccines

Immunomodulatory and biological properties of helminth-derived small molecules: Potential applications in diagnostics and therapeutics

Parasitic helminths secrete and excrete a vast array of molecules known to help skew or suppress the host's immune response, thereby establishing a niche for sustained parasite maintenance. Indeed, the immunomodulatory potency of helminths is attributed mainly to excretory/secretory products (ESPs). The ESPs of helminths and the identified small molecules (SM) are reported to have diverse biological and pharmacological properties. The available literature reports only limited metabolites, and the identity of many metabolites remains unknown due to limitations in the identification protocols and helminth-specific compound libraries. Many metabolites are known to be involved in host-parasite interactions and pathogenicity. For example, fatty acids (e.g., stearic acid) detected in the infective stages of helminths are known to have a role in host interaction through facilitating successful penetration and migration inside the host. Moreover, excreted/secreted SM detected in helminth species are found to possess various biological properties, including anti-inflammatory activities, suggesting their potential in developing immunomodulatory drugs. For example, helminths-derived somatic tissue extracts and whole crude ESPs showed anti-inflammatory properties by inhibiting the secretion of proinflammatory cytokines from human peripheral blood mononuclear cells and suppressing the pathology in chemically-induced experimental mice model of colitis. Unlike bigger molecules like proteins, SM are ideal candidates for drug development since they are small structures, malleable, and lack immunogenicity. Future studies should strive toward identifying unknown SM and isolating the under-explored niche of helminth metabolites using the latest metabolomics technologies and associated software, which hold potential keys for finding new diagnostics and novel therapeutics.

Using Caenorhabditis elegans to produce functional secretory proteins of parasitic nematodes

The expression of antigens in their immunologically-active form remains a challenge, both in the analysis of regulatory pathways exploited by parasitic nematodes or in the development of vaccines. Despite the success of native proteins to induce protective immunity, recombinant proteins expressed in bacteria, yeast or insect cells offer only limited protective capacities, presumably due to incorrect folding or missing complex posttranslational modifications. The present study investigates the feasibility of using the free-living nematode Caenorhabditis elegans as an alternative expression system for proteins found in the secretome of parasitic nematodes. Exemplified by the expression of the extracellular superoxide dismutase from Haemonchus contortus (HcSODe) and the extracellular and glycosylated glutathione S-transferase from the filarial parasite Onchocerca volvulus (OvGST1), we continue our efforts to improve production and purification of recombinant proteins expressed in C. elegans. We demonstrate that sufficient quantities of functional proteins can be expressed in C. elegans for subsequent immunological and biochemical studies.

Oral delivery of a functional algal-expressed TGF-β mimic halts colitis in a murine DSS model

Inflammatory bowel disease (IBD) is a set of immunological disorders which can generate chronic pain and fatigue associated with the inflammatory symptoms. The treatment of IBD remains a significant hurdle with current therapies being only partially effective or having significant side effects, suggesting that new therapies that elicit different modes of action and delivery strategies are required. TGM1 is a TGF-β mimic that was discovered from the intestinal helminth parasite Heligmosomoides polygyrus and is thought to be produced by the parasite to suppress the intestinal inflammation response to help evade host immunity, making it an ideal candidate to be developed as a novel anti-inflammatory bio-therapeutic. Here we utilized the expression system of the edible green algae Chlamydomonas reinhardtii in order to recombinantly produce active TGM1 in a form that could be ingested. C. reinhardtii robustly expressed TGM1, and the resultant recombinant protein is biologically active as measured by regulatory T cell induction. When delivered orally to mice, the algal expressed TGM1 is able to ameliorate weight loss, lymphadenopathy, and disease symptoms in a mouse model of DSS-induced colitis, demonstrating the potential of this biologic as a novel treatment of IBD.

Onchocerciasis (river blindness) - more than a century of research and control

This review summarises more than a century of research on onchocerciasis, also known as river blindness, and its control. River blindness is an infection caused by the tissue filaria Onchocerca volvulus affecting the skin, subcutaneous tissue and eyes and leading to blindness in a minority of infected persons. The parasite is transmitted by its intermediate hosts Simulium spp. which breed in rivers. Featured are history and milestones in onchocerciasis research and control, state-of-the-art data on the parasite, its endobacteria Wolbachia, on the vectors, previous and current prevalence of the infection, its diagnostics, the interaction between the parasite and its host, immune responses and the pathology of onchocerciasis. Detailed information is documented on the time course of control programmes in the afflicted countries in Africa and the Americas, a long road from previous programmes to current successes in control of the transmission of this infectious disease. By development, adjustment and optimization of the control measures, transmission by the vector has been interrupted in foci of countries in the Americas, in Uganda, in Sudan and elsewhere, followed by onchocerciasis eliminations. The current state and future perspectives for control, elimination and eradication within the next 20-30 years are described and discussed. This review contributes to a deeper comprehension of this disease by a tissue-dwelling filaria and it will be helpful in efforts to control and eliminate other filarial infections.

Schistosome and intestinal helminth modulation of macrophage immunometabolism

Macrophages are fundamental to sustain physiological equilibrium and to regulate the pathogenesis of parasitic and metabolic processes. The functional heterogeneity and immune responses of macrophages are shaped by cellular metabolism in response to the host's intrinsic factors, environmental cues and other stimuli during disease. Parasite infections induce a complex cascade of cytokines and metabolites that profoundly remodel the metabolic status of macrophages. In particular, helminths polarize macrophages to an M2 state and induce a metabolic shift towards reliance on oxidative phosphorylation, lipid oxidation and amino acid metabolism. Accumulating data indicate that helminth-induced activation and metabolic reprogramming of macrophages underlie improvement in overall whole-body metabolism, denoted by improved insulin sensitivity, body mass in response to high-fat diet and atherogenic index in mammals. This review aims to highlight the metabolic changes that occur in human and murine-derived macrophages in response to helminth infections and helminth products, with particular interest in schistosomiasis and soil-transmitted helminths.

Galectins from Onchocerca ochengi and O. volvulus and their immune recognition by Wistar rats, Gudali zebu cattle and human hosts

Background

During the last two decades research on animal filarial parasites, especially Onchocerca ochengi, infecting cattle in savanna areas of Africa revealed that O. ochengi as an animal model has biological features that are similar to those of O. volvulus, the aetiological agent of human onchocerciasis. There is, however, a paucity of biochemical, immunological and pathological data for O. ochengi. Galectins can be generated by parasites and their hosts. They are multifunctional molecules affecting the interaction between filarial parasites and their mammalian hosts including immune responses. This study characterized O. ochengi galectin, verified its immunologenicity and established its immune reactivity and that of Onchocerca volvulus galectin.

Results

The phylogenetic analysis showed the high degree of identity between the identified O. ochengi and the O. volvulus galectin-1 (ß-galactoside-binding protein-1) consisting only in one exchange of alanine for serine. O. ochengi galectin induced IgG antibodies during 28 days after immunization of Wistar rats. IgG from O. ochengi-infected cattle and O. volvulus-infected humans cross-reacted with the corresponding galectins. Under the applied experimental conditions in a cell proliferation test, O. ochengi galectin failed to significantly stimulate peripheral blood mononuclear cells (PBMCs) from O. ochengi-infected cattle, regardless of their parasite load.

Conclusion

An O. ochengi galectin gene was identified and the recombinantly expressed protein was immunogenic. IgG from Onchocerca-infected humans and cattle showed similar cross-reaction with both respective galectins. The present findings reflect the phylogenetic relationship between the two parasites and endorse the appropriateness of the cattle O. ochengi model for O. volvulus infection research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-020-02064-3.

Fasciola hepatica-derived molecules as potential immunomodulators

Through the years, helminths have co-existed with many species. This process has allowed parasites to live within them for long periods and, in some cases, to generate offspring. In particular, this ability has allowed Fasciola hepatica to survive the diverse immunological responses faced within its wide range of hosts. The vast repertoire of molecules that are constantly secreted in large quantities by the parasite, acts directly on several cells of the immune system affecting their antiparasitic capacities. Interestingly, these molecules can direct the host immune response to an anti-inflammatory and regulatory phenotype that assures the survival of the parasite with less harm to the host. Based on these observations, some of the products of F. hepatica, as well as those of other helminths, have been studied, either as a total extract, extracellular vesicles or as purified molecules, to establish and characterize their anti-inflammatory mechanisms. Until now, the results obtained encourage further research directed to discover new helminth-derived alternatives to replace current therapies, which can be useful for people suffering from inflammatory diseases like autoimmunity or allergy processes that affect their life quality. In this review, some of the most studied molecules derived from F. hepatica and their modulating capacities are discussed.

Gut microecology: Why our microbes could be key to our health

The human body contains a large number of microorganisms, and the gut microecology environment contains the largest number and types of microorganisms. The structure and function of gut microbiota are closely related to the health of the human body. In a cascade of studies, the diversity of gut microbiota and its metabolite often found changed in patients or mice model. What kind of gut microbiota that associated with the occurrence or treatment of diseases were also found in many studies. Gut microbiota and its products can affect the function of the human body. Short-chain fatty acids, bile acid, indoles and so on were found can regulate the inflammation, immune response to affect the process of diseases. Immune cells like natural killer T cells, CD3 + T cells were also found had a link to gut microbiota which associated with diseases. Changes in gut microbiota are associated with changes in the body's major systems, such as the digestive system, the endocrine system, the cardiovascular system, the endocrine and metabolic system, the urinary system diseases, the respiratory system and so on. It is of great significance to study gut microecology for the prevention and treatment of various human diseases.

Trichinella spiralis: inflammation modulator

The hygiene hypothesis posits that the decreased incidence of parasitic infection in developed countries may underlie an increased prevalence of allergic and autoimmune diseases in these countries. As unique inflammation modulator of intracellular parasitism, Trichinella spiralis, or its excretory-secretory (ES) product, shows improved responses to allergies, autoimmune diseases, inflammatory bowel disease, type 1 diabetes, rheumatic arthritis and autoimmune encephalomyelitis by exerting immunomodulatory effects on both innate and adaptive immune cells in animal models. Research has shown that T. spiralis differs from other helminths in manipulation of the host immune response not only by well-known characteristics of its life cycle, but also by its inflammation modulation pathway. How the parasite achieves inflammation modulation has not been fully elucidated yet. This review will generalize the mechanism and focuses on ES immunomodulatory molecules of T. spiralis that may be important for developing new therapeutics for inflammatory disorders.

Fasciola hepatica-Derived Molecules as Regulators of the Host Immune Response

Helminths (worms) are one of the most successful organisms in nature given their ability to infect millions of humans and animals worldwide. Their success can be attributed to their ability to modulate the host immune response for their own benefit by releasing excretory-secretory (ES) products. Accordingly, ES products have been lauded as a potential source of immunomodulators/biotherapeutics for an array of inflammatory diseases. However, there is a significant lack of knowledge regarding the specific interactions between these products and cells of the immune response. Many different compounds have been identified within the helminth "secretome," including antioxidants, proteases, mucin-like peptides, as well as helminth defense molecules (HDMs), each with unique influences on the host inflammatory response. HDMs are a conserved group of proteins initially discovered in the secretome of the liver fluke, Fasciola hepatica. HDMs interact with cell membranes without cytotoxic effects and do not exert antimicrobial activity, suggesting that these peptides evolved specifically for immunomodulatory purposes. A peptide generated from the HDM sequence, termed FhHDM-1, has shown extensive anti-inflammatory abilities in clinically relevant models of diseases such as diabetes, multiple sclerosis, asthma, and acute lung injury, offering hope for the development of a new class of therapeutics. In this review, the current knowledge of host immunomodulation by a range of F. hepatica ES products, particularly FhHDM-1, will be discussed. Immune regulators, including HDMs, have been identified from other helminths and will also be outlined to broaden our understanding of the variety of effects these potent molecules exert on immune cells.

Excretory/Secretory Metabolome of the Zoonotic Roundworm Parasite Toxocara canis

Toxocariasis is a zoonotic disease affecting humans that is predominantly caused by Toxocara canis and T. cati, primarily parasites of dogs and cats, respectively. Toxocara generally establishes long-term infections by co-opting its host's physiological processes, while at the same time exploiting the nutritional environment. Adult stage T. canis reside in the gut of the definitive canine host where they employ a suite of strategies to combat intestinal immune responses by actively producing and releasing excretory-secretory products (ESPs). The protein component of T. canis ESPs has been widely studied, but characterisation of the non-protein ESP complement remains neglected. To characterize the secreted metabolome of Toxocara ESPs and to shed light on the parasite's metabolic processes, we profiled the ESPs of T. canis using both gas chromatography (GC) and liquid chromatography (LC) mass spectrometry approaches. We successfully identified 61 small molecules, including 41 polar metabolites, 14 medium-long chain fatty acids (MLCFAs) and six short chain fatty acids (SCFAs). We identified talose, stearic acid and isovalerate as the major compounds belonging to the polar, MLCFA and SCFA chemical classes, respectively. Most of the 61 identified metabolites appear to have been produced by T. canis via three distinct metabolic pathways - fatty acid, amino acid and carbohydrate metabolism. The majority of the identified ESPs have known biological properties, especially as immunomodulators. However, there is limited/no information on the biological roles or applications of 31 ESP biomolecules, suggesting that these may have novel activities that merit further investigation.

Harnessing helminth-driven immunoregulation in the search for novel therapeutic modalities

Parasitic helminths have coevolved with humans over millennia, intricately refining and developing an array of mechanisms to suppress or skew the host’s immune system, thereby promoting their long-term survival. Some helminths, such as hookworms, cause little to no overt pathology when present in modest numbers and may even confer benefits to their human host. To exploit this evolutionary phenomenon, clinical trials of human helminth infection have been established and assessed for safety and efficacy for a range of immune dysfunction diseases and have yielded mixed outcomes. Studies of live helminth therapy in mice and larger animals have convincingly shown that helminths and their excretory/secretory products possess anti-inflammatory drug-like properties and represent an untapped pharmacopeia. These anti-inflammatory moieties include extracellular vesicles, proteins, glycans, post-translational modifications, and various metabolites. Although the concept of helminth-inspired therapies holds promise, it also presents a challenge to the drug development community, which is generally unfamiliar with foreign biologics that do not behave like antibodies. Identification and characterization of helminth molecules and vesicles and the molecular pathways they target in the host present a unique opportunity to develop tailored drugs inspired by nature that are efficacious, safe, and have minimal immunogenicity. Even so, much work remains to mine and assess this out-of-the-box therapeutic modality. Industry-based organizations need to consider long-haul investments aimed at unraveling and exploiting unique and differentiated mechanisms of action as opposed to toe-dipping entries with an eye on rapid and profitable turnarounds.

Isolation and Functions of Extracellular Vesicles Derived from Parasites: The Promise of a New Era in Immunotherapy, Vaccination, and Diagnosis

Experimental and epidemiological evidence shows that parasites, particularly helminths, play a central role in balancing the host immunity. It was demonstrated that parasites can modulate immune responses via their excretory/secretory (ES) and some specific proteins. Extracellular vesicles (EVs) are nano-scale particles that are released from eukaryotic and prokaryotic cells. EVs in parasitological studies have been mostly employed for immunotherapy of autoimmune diseases, vaccination, and diagnosis. EVs can carry virulence factors and play a central role in the development of parasites in host cells. These molecules can manipulate the immune responses through transcriptional changes. Moreover, EVs derived from helminths modulate the immune system via provoking anti-inflammatory cytokines. On the other hand, EVs from parasite protozoa can induce efficient immunity, that makes them useful for probable next-generation vaccines. In addition, it seems that EVs from parasites may provide new diagnostic approaches for parasitic infections. In the current study, we reviewed isolation methods, functions, and applications of parasite's EVs in immunotherapy, vaccination, and diagnosis.

Revisiting Inflammatory Bowel Disease: Pathology, Treatments, Challenges and Emerging Therapeutics Including Drug Leads from Natural Products

Inflammatory bowel disease (IBD) is a chronic and life-long disease characterized by gastrointestinal tract inflammation. It is caused by the interplay of the host's genetic predisposition and immune responses, and various environmental factors. Despite many treatment options, there is no cure for IBD. The increasing incidence and prevalence of IBD and lack of effective long-term treatment options have resulted in a substantial economic burden to the healthcare system worldwide. Biologics targeting inflammatory cytokines initiated a shift from symptomatic control towards objective treatment goals such as mucosal healing. There are seven monoclonal antibody therapies excluding their biosimilars approved by the US Food and Drug Administration for induction and maintenance of clinical remission in IBD. Adverse side effects associated with almost all currently available drugs, especially biologics, is the main challenge in IBD management. Natural products have significant potential as therapeutic agents with an increasing role in health care. Given that natural products display great structural diversity and are relatively easy to modify chemically, they represent ideal scaffolds upon which to generate novel therapeutics. This review focuses on the pathology, currently available treatment options for IBD and associated challenges, and the roles played by natural products in health care. It discusses these natural products within the current biodiscovery research agenda, including the applications of drug discovery techniques and the search for next-generation drugs to treat a plethora of inflammatory diseases, with a major focus on IBD.

Regulation of immunity and allergy by helminth parasites

There is increasing interest in helminth parasite modulation of the immune system, both from the fundamental perspective of the "arms race" between host and parasite, and equally importantly, to understand if parasites offer new pathways to abate and control untoward immune responses in humans. This article reviews the epidemiological and experimental evidence for parasite down-regulation of host immunity and immunopathology, in allergy and other immune disorders, and recent progress towards defining the mechanisms and molecular mediators which parasites exploit in order to modulate their host. Among these are novel products that interfere with epithelial cell alarmins, dendritic cell activation, macrophage function and T-cell responsiveness through the promotion of an immunoregulatory environment. These modulatory effects assist parasites to establish and survive, while dampening immune reactivity to allergens, autoantigens and microbiome determinants.

Potential application of helminth therapy for resolution of neuroinflammation in neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are among the major debilitating disorders worldwide with multiple etiological factors. However, in recent years, psychoneuroimmunology uncovered the role of inflammatory condition and autoimmune disorders in the etiopathogenesis of different NPDs. Hence, resolution of inflammation is a new therapeutic target of NPDs. On the other hand, Helminth infections are among the most prevalent infectious diseases in underdeveloped countries, which usually caused chronic infections with minor clinical symptoms. Remarkably, helminths are among the master regulator of inflammatory reactions and epidemiological studies have shown an inverse association between prevalence of autoimmune disorders with these infections. As such, changes of intestinal microbiota are known to be associated with inflammatory conditions in various NPDs. Conversely, helminth colonization alters the intestinal microbiota composition that leads to suppression of intestinal inflammation. In animal models and human studies, helminths or their antigens have shown to be protected against severe autoimmune and allergic disorders, decline the intensity of inflammatory reactions and improved clinical symptoms of the patients. Therefore, "helminthic therapy" have been used for modulation of immune disturbances in different autoimmunity illnesses, such as Multiple Sclerosis (MS) and Inflammatory Bowel Disease (IBD). Here, it is proposed that "helminthic therapy" is able to ameliorate neuroinflammation of NPDs through immunomodulation of inflammatory reactions and alteration of microbiota composition. This review discusses the potential application of "helminthic therapy" for resolution of neuroinflammation in NPDs.

Cystatin from Filarial Parasites Suppress the Clinical Symptoms and Pathology of Experimentally Induced Colitis in Mice by Inducing T-Regulatory Cells, B1-Cells, and Alternatively Activated Macrophages

Potential alternative therapeutic strategies for immune-mediated disorders are being increasingly recognized and are studied extensively. We previously reported the therapeutic potential of Brugia malayi derived recombinant cystatin (rBmaCys) in attenuating clinical symptoms of experimental colitis. The aim of this study was to elucidate the mechanisms involved in the rBmaCys-induced suppression of inflammation in the colon. Our results show that, the frequency of CD4⁺CD25⁺FoxP3⁺ regulatory T-cells was elevated in the colon and mesenteric lymph nodes. Similarly, the peritoneal macrophages recovered from the rBmaCys-treated colitis mice were alternatively activated and displayed reduced expression of TNF-α and IL-6. Another finding was significant increases in IgM⁺B1a-cells in the peritoneal cavity of mice following rBmaCys-treatment. These findings suggested that the regulatory cell network promoted by the rBmaCys in the colon and associated lymphoid tissues is important for its anti-inflammatory activity in the dextran sulfate sodium (DSS)-induced colitis mice.

Neuronal impairment following chronic Toxoplasma gondii infection is aggravated by intestinal nematode challenge in an IFN-γ-dependent manner

Background

It has become increasingly evident that the immune and nervous systems are closely intertwined, relying on one another during regular homeostatic conditions. Prolonged states of imbalance between neural and immune homeostasis, such as chronic neuroinflammation, are associated with a higher risk for neural damage. Toxoplasma gondii is a highly successful neurotropic parasite causing persistent subclinical neuroinflammation, which is associated with psychiatric and neurodegenerative disorders. Little is known, however, by what means neuroinflammation and the associated neural impairment can be modulated by peripheral inflammatory processes.

Methods

Expression of immune and synapse-associated genes was assessed via quantitative real-time PCR to investigate how T. gondii infection-induced chronic neuroinflammation and associated neuronal alterations can be reshaped by a subsequent acute intestinal nematode co-infection. Immune cell subsets were characterized via flow cytometry in the brain of infected mice. Sulfadiazine and interferon-γ-neutralizing antibody were applied to subdue neuroinflammation.

Results

Neuroinflammation induced by T. gondii infection of mice was associated with increased microglia activation, recruitment of immune cells into the brain exhibiting Th1 effector functions, and enhanced production of Th1 and pro-inflammatory molecules (IFN-γ, iNOS, IL-12, TNF, IL-6, and IL-1β) following co-infection with Heligmosomoides polygyrus. The accelerated cerebral Th1 immune response resulted in enhanced T. gondii removal but exacerbated the inflammation-related decrease of synapse-associated gene expression. Synaptic proteins EAAT2 and GABA_Aα1, which are involved in the excitation/inhibition balance in the CNS, were affected in particular. These synaptic alterations were partially recovered by reducing neuroinflammation indirectly via antiparasitic treatment and especially by application of IFN-γ-neutralizing antibody. Impaired iNOS expression following IFN-γ neutralization directly affected EAAT2 and GABA_Aα1 signaling, thus contributing to the microglial regulation of neurons. Besides, reduced CD36, TREM2, and C1qa gene expression points toward inflammation induced synaptic pruning as a fundamental mechanism.

Conclusion

Our results suggest that neuroimmune responses following chronic T. gondii infection can be modulated by acute enteric nematode co-infection. While consecutive co-infection promotes parasite elimination in the CNS, it also adversely affects gene expression of synaptic proteins, via an IFN-γ-dependent manner.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1539-8) contains supplementary material, which is available to authorized users.

Metabolomic profiling of the excretory-secretory products of hookworm and whipworm

INTRODUCTION

Soil-transmitted helminths infect billions of people, livestock and companion animals worldwide, and chronic infections with these nematodes represent a major health burden in many developing countries. On the other hand, complete elimination of parasitic helminths and other infectious pathogens has been implicated with rising rates of autoimmune and allergic disorders in developed countries. Given the enormous health impact of these parasites, it is surprising how little is known about the non-protein small metabolites of the excretory-secretory products (ESP), including their composition and pharmacological properties.

OBJECTIVES

We sought proof-of-concept that Nippostrongylus brasiliensis and Trichuris muris, rodent models of two of the most important human soil-transmitted helminths, secrete small metabolites and that some of these metabolites may have specific pharmacological functions.

METHODS

N. brasiliensis and T. muris ESP were collected from adult worms and filtered using a 10 kDa cut-off membrane to produce excretory-secretory metabolites (ESM). The ESM were analysed using targeted gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry for polar and non-polar small metabolites.

RESULTS

ESM from both N. brasiliensis and T. muris contained small molecules. A total of 54 small molecules (38 polar metabolites and 16 fatty acids) were identified, 36 known polar metabolites from N. brasiliensis and 35 from T. muris. A literature review of the identified compounds revealed that 17 of them have various demonstrated pharmacological activities.

CONCLUSION

N. brasiliensis and T. muris secrete polar and non-polar small molecules with as many as 17 metabolites known to exhibit various pharmacological activities.

Allergy in an Evolutionary Framework

Respiratory allergy including bronchial asthma and food allergy have gained epidemic character in the last decades in industrialized countries. Much has been learned with respect to the pathophysiology of allergic disease and this has facilitated specific therapies. Allergy is a chronic disease, and being so prevalent claims to search for evolutionary causes of the general susceptibility of humans as a species to react to environmental antigens in a Th2 type immune reaction with IgE production. In an evolutionary analysis of Allergy, necessary questions addressed in this review are "Why does IgE exist or why did IgE evolve?" as well as from the point of view of the mismatch hypothesis, "Why is there an Allergy epidemic?" Recent studies on the possible biological and protective role of IgE against parasites, arthropods, venoms or toxins are challenging the widely accepted definition of allergens as generally innocuous antigens. Combining the immunologic danger model and the toxin hypothesis for allergies, the allergic response could have evolved with an adaptive value and allergens could be proxies for other putative noxious agents. The last decades yielded with vast molecular data of allergens. With available bioinformatics tools, we therefore also describe that evolutionary theory could be applied to prevent allergy, estimate cross-reactivity, to design allergen-specific immunotherapy and to assess the risks of novel foods.

Helminth Therapy - From the Parasite Perspective

Studies in animal models and humans suggest that intentional exposure to helminths or helminth-derived products may hold promise for treating chronic inflammatory-associated diseases (CIADs). Although the mechanisms underlying 'helminth therapy' are being evaluated, little attention has been paid to the actual organisms in use. Here we examine the notion that, because of the complexity of biological symbiosis, intact helminths rather than helminth-derived products are likely to prove more useful for clinical purposes. Further, weighing potential cost/benefit ratios of various helminths along with other factors, such as feasibility of production, we argue that the four helminths currently in use for CIAD treatments in humans were selected more by happenstance than by design, and that other candidates not yet tested may prove superior.

Frontiers in Molecular Evolutionary Medicine

This paper surveys some of the important insights that molecular evolution has contributed to evolutionary medicine; they include phage therapy, cancer biology, helminth manipulation of the host immune system, quality control of gametes, and pathogen outbreaks. Molecular evolution has helped to revolutionize our understanding of cancer, of autoimmune disease, and of the origin, spread, and pathogenesis of emerging diseases, where it has suggested new therapies, illuminated mechanisms, and revealed historical processes: all have practical therapeutic implications. While much has been accomplished, much remains to be done.

Tolerising cellular therapies: what is their promise for autoimmune disease?

The current management of autoimmunity involves the administration of immunosuppressive drugs coupled to symptomatic and functional interventions such as anti-inflammatory therapies and hormone replacement. Given the chronic nature of autoimmunity, however, the ideal therapeutic strategy would be to reinduce self-tolerance before significant tissue damage has accrued. Defects in, or defective regulation of, key immune cells such as regulatory T cells have been documented in several types of human autoimmunity. Consequently, it has been suggested that the administration of ex vivo generated, tolerogenic immune cell populations could provide a tractable therapeutic strategy. Several potentially tolerogenic cellular therapies have been developed in recent years; concurrent advances in cell manufacturing technologies promise scalable, affordable interventions if safety and efficacy can be demonstrated. These therapies include mesenchymal stromal cells, tolerogenic dendritic cells and regulatory T cells. Each has advantages and disadvantages, particularly in terms of the requirement for a bespoke versus an 'off-the-shelf' treatment but also their suitability in particular clinical scenarios. In this review, we examine the current evidence for these three types of cellular therapy, in the context of a broader discussion around potential development pathway(s) and their likely future role. A brief overview of preclinical data is followed by a comprehensive discussion of human data.

Schistosome Egg Migration: Mechanisms, Pathogenesis and Host Immune Responses

Many parasitic worms possess complex and intriguing life cycles, and schistosomes are no exception. To exit the human body and progress to their successive snail host, Schistosoma mansoni eggs must migrate from the mesenteric vessels, across the intestinal wall and into the feces. This process is complex and not always successful. A vast proportion of eggs fail to leave their definite host, instead becoming lodged within intestinal or hepatic tissue, where they can evoke potentially life-threatening pathology. Thus, to maximize the likelihood of successful egg passage whilst minimizing host pathology, intriguing egg exit strategies have evolved. Notably, schistosomes actively exert counter-inflammatory influences on the host immune system, discreetly compromise endothelial and epithelial barriers, and modulate granuloma formation around transiting eggs, which is instrumental to their migration. In this review, we discuss new developments in our understanding of schistosome egg migration, with an emphasis on S. mansoni and the intestine, and outline the host-parasite interactions that are thought to make this process possible. In addition, we explore the potential immune implications of egg penetration and discuss the long-term consequences for the host of unsuccessful egg transit, such as fibrosis, co-infection and cancer development.